Electrical antifuse including phase change material

ABSTRACT

An antifuse structure including a first electrode that is present in at a base of the opening in the dielectric material. The antifuse structure further includes an antifuse material layer comprising a phase change material alloy of tantalum and nitrogen. A first surface of the antifuse material layer is present in direct contact with the first electrode. A second electrode is present in direct contact with a second surface of the antifuse material layer that is opposite the first surface of the antifuse material layer.

BACKGROUND

Technical Field

The present disclosure relates to antifuse structures, and moreparticularly to antifuse structures including materials in which theresistance of the material may be adjusted.

Description of the Related Art

Antifuse structures have been used in the semiconductor industry formemory related applications such as, for example, field programmablegate arrays and programmable read-only memories. Most existing antifusestructures have a layer of antifuse material sandwiched in between twodisconnected conductive materials. In such structures, the antifusestructure/circuit initially has a very high resistance, but afterprogramming by electrical or optical means, the high resistancestructure/circuit is converted to a lower resistance state.

SUMMARY

In one aspect, the present disclosure provides an antifuse structurethat includes an antifuse material layer composed of an alloy oftantalum and nitrogen that changes from an insulating phase to anelectrically conductive phase in response to thermal heating. In oneembodiment, the antifuse structure may include a first electricallyconductive material that is present within an opening in a dielectricmaterial, and an antifuse material layer present within the opening inthe dielectric. The antifuse material layer may include a phase changematerial alloy of tantalum and nitrogen. At least one surface of theantifuse material layer is present in direct contact with the firstelectrically conductive material. A second electrically conductivematerial is present in direct contact with at least the antifusematerial layer. The second electrically conductive material is alsopresent over the opening.

In another aspect of the present disclosure, an electrical device isprovided including an antifuse structure composed of an antifusematerial layer of an alloy of tantalum and nitrogen that changes from aninsulating phase to an electrically conductive phase in response tothermal heating. In one embodiment, the antifuse structure includes adielectric layer atop an electrical device, wherein an opening extendsthrough the dielectric layer to a contact surface of the electricaldevice. In some embodiments, a diffusion barrier may be present onsidewalls and a base of the opening. An antifuse material layer may bepresent within the opening in the dielectric layer. In some embodiments,the antifuse material layer is composed of a phase change material alloyof tantalum and nitrogen. The antifuse material layer may fill anentirety of the opening. An electrically conductive material is presentin direct contact with at least the antifuse material layer. Theelectrically conductive material layer extends over the antifusematerial layer and the dielectric layer.

In yet another aspect of the present disclosure, a method of forming anantifuse is provided in which the antifuse structure is composed of anantifuse material layer of an alloy of tantalum and nitrogen thatchanges from an insulating phase to an electrically conductive phase inresponse to thermal heating. In one embodiment, the method includesforming at least one opening through a dielectric layer that extends toa contact for an electrical device. An antifuse material layer is thenformed comprising a phase change material alloy of tantalum andnitrogen. The antifuse material layer fills at least a portion of theopening. The phase change material may be programmed thermally.

In another aspect of the present disclosure, a method of programming anantifuse structure is provided that includes providing an antifusematerial layer including a phase change material alloy of tantalum andnitrogen in an opening through a dielectric layer to an electricaldevice. The phase change material alloy is formed with an insulatingphase in an unprogrammed state. The antifuse material layer is contactedwith an electrically conductive metal at a surface of the antifusematerial layer that is opposite a surface of the antifuse material layerthat is contacting the electrical device. The antifuse material may bethermally heated through the electrically conductive metal. Thermallyheating the antifuse material changes crystal structure (and accordinglychanges a nitrogen (N) to tantalum (Ta) ratio) in the antifuse materiallayer to provide electrical conductivity.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The disclosure will provide details in the following description ofpreferred embodiments with reference to the following figures wherein:

FIG. 1A is a side cross-sectional view depicting one embodiment of anantifuse structure including an antifuse material layer of a phasechange alloy including tantalum and nitrogen that is present within anopening extending through a dielectric layer, wherein the antifusematerial layer is underlying an electrically conductive material layerthat extends over the opening and the antifuse material layer is presentatop another electrically conductive material layer that is presentwithin the opening, in accordance with one embodiment of the presentdisclosure.

FIG. 1B is a side cross-sectional view depicting another embodiment ofan antifuse structure including an antifuse material layer of a phasechange alloy including tantalum and nitrogen that is present filling theentirety of the opening extending through a dielectric layer, inaccordance with one embodiment of the present disclosure.

FIG. 2A is a side cross-sectional view depicting another embodiment ofan antifuse structure, in which the antifuse material of the phasechange alloy including tantalum and nitrogen is present centrallypositioned within the opening extending through the dielectric layer,wherein the antifuse material is substantially surrounded by anelectrically conductive material present between the sidewalls of theopening and the centrally positioned antifuse material as well as aportion of the electrically conductive material that is present at thebase of the opening, in accordance with one embodiment of the presentdisclosure.

FIG. 2B is a side cross-sectional view depicting another embodiment ofthe antifuse structure, in which the antifuse material of the phasechange alloy that includes tantalum and nitrogen is centrally positionedwithin an opening extending through the dielectric layer, the antifusematerial extending through an entirety of the vertical height of theopening, in accordance with the present disclosure.

FIG. 3A is a side cross-sectional view depicting one embodiment of anantifuse structure in which the antifuse material of the phase changealloy including tantalum and nitrogen is centrally positioned within anopening in the dielectric layer, and has a tapered sidewall, wherein theantifuse material is substantially surrounded by an electricallyconductive material, in accordance with one embodiment of the presentdisclosure.

FIG. 3B is a side cross-sectional view depicting one embodiment of anantifuse structure, in which the antifuse material of the phase changealloy of tantalum and nitrogen is centrally positioned within an openingin the dielectric layer that has a tapered sidewall and extends throughan entirety of the vertical height of the opening, in accordance withthe present disclosure.

FIG. 4 is a side cross-sectional view of a via contact through adielectric layer to an electrical device, in accordance with oneembodiment of the present disclosure.

FIG. 5A is a side cross-sectional view of recessing the electricallyconductive material of a via contact structure within a via openingthrough a dielectric layer to an underlying contact to an electricaldevice, wherein a portion of the electrically conductive material at thebase of the via opening remains, in accordance with one embodiment ofthe present disclosure.

FIG. 5B is a side cross-sectional view of removing the electricallyconductive material of a via contact structure within a via openingthrough a dielectric layer to an underlying contact to an electricaldevice, in accordance with one embodiment of the present disclosure.

FIG. 6A is a side cross-sectional view of forming an antifuse materiallayer of a phase change alloy of tantalum and nitrogen in the upperportion of the via opening that is depicted in FIG. 5A.

FIG. 6B is a side cross-sectional view of forming an antifuse materiallayer of a phase change alloy of tantalum and nitrogen, in which theantifuse material layer fills an entirety of the via opening that isdepicted in FIG. 5B.

FIG. 7A is a side cross-sectional view depicting forming a metal line,i.e., a layer of an electrically conductive material, atop the viacontact depicted in FIG. 4, in accordance with the present disclosure.

FIG. 7B is a side cross-sectional view depicting forming a metal lineatop an antifuse material layer of a phase change material includingtantalum and nitrogen that is present in a via opening through adielectric layer, as depicted in FIG. 6A.

FIG. 7C is a side cross-sectional view depicting forming a metal lineatop an antifuse material layer of a phase change material includingtantalum and nitrogen that is present in a via opening through adielectric layer, as depicted in FIG. 6A.

FIG. 8A is a side cross-sectional view depicting forming an etch maskatop a contact via, as depicted in FIG. 4 for forming one of thestructures depicted in FIGS. 2A-3B, in accordance with anotherembodiment of the present disclosure.

FIG. 8B is a side cross-sectional view depicting one embodiment ofetching the electrically conductive material of the via contact depictedin FIG. 8A to provide an antifuse material opening, in which a portionof the electrically conductive material of the via contact remains onsidewalls of the via opening and at the base of the via opening, inaccordance with the present disclosure.

FIG. 8C is a side cross-sectional view depicting one embodiment ofetching the electrically conductive material of the via contact depictedin FIG. 8A, in which a portion of the electrically conductive materialof the contact remains on sidewalls of the via opening, but the antifusematerial opening extends through an entire height of the via opening.

FIG. 8D is a side cross-sectional view depicting one embodiment ofetching the electrically conductive material of the via contact depictedin FIG. 8A to provide an antifuse material opening having taperedsidewalls, in which a portion of the electrically conductive material ofthe via contact remains on sidewalls of the via opening and at the baseof the via opening, in accordance with the present disclosure.

FIG. 8E is a side cross-sectional view depicting one embodiment ofetching the electrically conductive material of the via contact depictedin FIG. 8A, in which a portion of the electrically conductive materialof the contact remains on sidewalls of the via opening, but the antifusematerial opening extends through an entire height of the via opening.

FIG. 9 is a side cross-sectional view depicting forming an antifusematerial layer of a phase change alloy of tantalum and nitrogen in theantifuse material opening depicted in FIG. 8B, in accordance with oneembodiment of the present disclosure.

FIG. 10 is a side cross-sectional view depicting planarizing theantifuse material layer depicted in FIG. 9.

DETAILED DESCRIPTION

Detailed embodiments of the claimed structures and methods are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely illustrative of the claimed structures and methods that maybe embodied in various forms. In addition, each of the examples given inconnection with the various embodiments is intended to be illustrative,and not restrictive. Further, the figures are not necessarily to scale,some features may be exaggerated to show details of particularcomponents. Therefore, specific structural and functional detailsdisclosed herein are not to be interpreted as limiting, but merely as arepresentative basis for teaching one skilled in the art to variouslyemploy the methods and structures of the present disclosure. Forpurposes of the description hereinafter, the terms “upper”, “lower”,“right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, andderivatives thereof shall relate to the embodiments of the disclosure,as it is oriented in the drawing figures. The terms “positioned on”means that a first element, such as a first structure, is present on asecond element, such as a second structure, wherein interveningelements, such as an interface structure, e.g. interface layer, may bepresent between the first element and the second element. The term“direct contact” means that a first element, such as a first structure,and a second element, such as a second structure, are connected withoutany intermediary conducting, insulating or semiconductor layers at theinterface of the two elements.

The present disclosure provides an antifuse structure, and methods offorming an antifuse structure devices including material layers thatexhibit changes in resistivity that correspond to phase changes. An“antifuse” is an electrical device that performs the opposite functionto a fuse. Whereas a fuse starts with a low resistance and is designedto permanently break an electrically conductive path (typically when thecurrent through the path exceeds a specified limit), an antifuse startswith a high resistance and can be designed to permanently create anelectrically conductive path (typically when the voltage across theantifuse exceeds a certain level). Antifuse structures include amaterial which initially has a high resistance but can be converted intoa lower resistance by the application of a certain process. Anun-programmmed antifuse type gate array is programmed by causing aselected antifuse to become conductive.

It has been determined that the process for integrating antifusestructures with other devices in an integrated circuit typicallyrequires extra masking and etching steps, which increases overallfabrication costs. It has also been determined that since theprogramming voltage for creating the electrical path in the antifuse isa function of the thickness of the antifuse layer, damage that is causedto the antifuse material resulting from over etch processes can resultin de-programming states, which can result in product failure, i.e., theelectrical path is not properly formed when the appropriate voltage isapplied. Moreover, the voltage programming method requires a stackedmultilayered structure in which a layer of antifuse material ispositioned between two “disconnected” conductive materials in anorientation that may be referred to as “sandwiched”. It has beendetermined that this geometry limits design flexability and enlarges thearea required for forming the antifuse material element.

In some embodiments, the methods and structures disclosed herein reducemanufacturing complexity of antifuse structures by providing antifusestructures without extra layers of antifuse materials. In someembodiments, the methods and structures disclosed herein include anantifuse material layer that is composed of an alloy of tantalum (Ta)and nitrogen (N). For example, the alloy of tantalum (Ta) and nitrogen(N) that may provide the antifuse material may be composed of tantalumnitride (Ta₃N₅). The alloys employed herein for the antifuse materialare phase change materials. More specifically, the tantalum (Ta) andnitrogen (N) alloy that provides the antifuse material layer disclosedherein, is typically deposited at a phase that provides insulatingproperties, which provides the state of the antifuse before programming.Programming of the antifuse may include heating the antifuse material,e.g., by heating the surrounding electrodes, which can cause a phasechange in the tantalum (Ta) and nitrogen (N) alloy to a higherconductivity phase. For example, while the Ta₃N₅ phase of the tantalum(Ta) and nitrogen (N) alloy has a high resistance typical of aninsulator, the TaN phase of the tantalum (Ta) and nitrogen (N) alloy hasa lower resistance typical of an electrical conductor. The Ta₃N₅ phaseof the tantalum (Ta) and nitrogen (N) alloy may be referred to as anorthorhombic phase, which may be considered as a dielectric material.The TaN phase of the tantalum (Ta) and nitrogen (N) alloy may bereferred to as a cubic or hexagonal phase, and may be considered anelectrical conductor. “Electrically conductive” and/or “electricalconductor” as used through the present disclosure means a materialtypically having a room temperature resistivity less than about 250μΩ-cm. As used herein, the terms “insulator” and “dielectric” denote amaterial having a room temperature resistivity greater than about 250μΩ-cm. The phase change from the insulating phases to the electricallyconductive phases is induced by crystal structure change throughheating. The conductivity of the anti-fuse element can be increased bychanging phase of the tantalum (Ta) and nitrogen (N) alloy, e.g., cubic,hexagonal, through heating, e.g., by heating the conductive materialscontacting the antifuse material, i.e., the antifuse material oftantalum (Ta) and nitrogen (N) alloy. The methods and structures of thepresent disclosure are now described with greater detail referring toFIGS. 1A-10.

FIG. 1A depicts one embodiment of an antifuse structure 100 including anantifuse material layer 10 of a phase change alloy including tantalumand nitrogen that is present within an opening 15 extending through adielectric layer 5. In some embodiments, the dielectric layer 5 is aninterlevel dielectric layer that is present overlying a contact surface25 to an electrical device, such as a semiconductor device, e.g., fieldeffect transistor (FET), fin type field effect transistor (FinFET),metal oxide semiconductor field effect transistor (MOSFET), bipolarjunction transistor, vertical finFET (V-FinFET); memory device, e.g.,dynamic random access memory (DRAM), embedded dynamic random accessmemory (eDRAM), flash memory; and/or passive electronic devices, such asresistors and capacitors. In some examples, the contact surface 25 maybe a gate structure or a source/drain region of a semiconductor device.The contact surface 25 may be any active region of a substrate to asemiconductor device. The opening 15 extends through the dielectriclayer 5 to a portion of the contact surface 25 of the electronic device.

In some embodiments, a diffusion barrier layer 30 (also referred to asfirst diffusion barrier layer 30) is present on the sidewalls of theopening 15 that is extending through the dielectric layer 5. The firstdiffusion barrier layer 30 may composed of a material composition thatobstructs the materials that are contained within the opening 15 fromdiffusing into the dielectric layer 5. For example, the first diffusionbarrier layer 30 may be composed of tantalum nitride (TaN). In otherexamples, the first diffusion barrier layer 30 may be composed of Co,Ir, Rh, Pt, Pd, Ta, TaN, Ti, TiN, Ru, RuN, RuTa, RuTaN, W, WN andcombinations thereof. In some embodiment, the diffusion barrier layer 30may have a conformal thickness ranging from 1 nm to 10 nm.

The antifuse material layer 10 of the phase change alloy includingtantalum (Ta) and nitrogen (N) is present entirely within the opening15, and does not extend outside the opening 15. The antifuse materiallayer 10 is also a single layer, and not a multilayered structure. Thesingle layer has a single composition of a tantalum (Ta) and nitrogen(N) alloy. By “phase change alloy” it is meant that the composition ofthe material layer can experience a change in phase from an electricallyinsulating phase to an electrically conductive phase. In someembodiments, the phase change may be induced thermally, e.g., bydirectly heating the phase change alloy. In some embodiment, theantifuse material layer 10 of the phase change alloy including tantalum(Ta) and nitrogen (N) is in a dielectric phase before programming. Thedielectric phase of the antifuse material layer 10 of the phase changealloy including tantalum (Ta) and nitrogen (N) may be Ta₃N₅, which maybe referred to as a dielectric material layer. When the alloy includingtantalum (Ta) and nitrogen (N) is in a dielectric phase, e.g., when thealloy composition is Ta₃N₅, the crystal structure of the tantalum (Ta)and nitrogen (N) alloy may be orthorhombic, which can be considered adielectric material. As will be described in greater detail below, inresponse to the application of heat, the antifuse material layer 10 ofthe phase change alloy including tantalum (Ta) and nitrogen (N) may beconverted into an electrically conductive phase. The conversion to theelectrically conductive phase may be referred to as programming. Whenprogrammed, the crystal structure of the antifuse material layer 10 ofthe phase change alloy including tantalum (Ta) and nitrogen (N) ischanged, e.g., Cubic, hexagonal. TaN. TaN is electrically conductive,and may have a cubic or hexagonal phase. The antifuse material layer 10may be a single composition material layer that extends the entire widthof the opening 15, and may directly contact the diffusion barrier 30that is present on the sidewalls of the dielectric layer 5.

In the embodiment that is depicted in FIG. 1A, the antifuse materiallayer 10 of a phase change alloy including tantalum (Ta) and nitrogen(N) includes at least one surface that is present in direct contact withan electrically conductive material 6 (also referred to as a firstelectrically conductive material 6) that is also present within theopening 15. In some embodiments, the first electrically conductivematerial 6 is present at the base of the opening 15 abutting the contactsurface 25, and the antifuse material layer 10 is present in the upperportion of the opening 15. In this embodiment, the first electricallyconductive material 6 is present as a layer in the lower portion of theopening 15 separating the antifuse material layer 10 from the contactsurface 25 to the electrical device. The first electrically conductivematerial 6 may be a single composition material layer that extends theentire width of the opening 15, and may directly contact the diffusionbarrier 30 that is present on the sidewalls of the dielectric layer 5.The first electrically conductive material 6 may be composed of a metalselected from copper (Cu), tungsten (W), aluminum (Al), cobalt (Co),rhodium (Rh), ruthenium (Ru), iridium (Ir), nickel (Ni) and combinationsthereof. In some embodiments, the first electrically conductive material6 may be used to thermally heat the antifuse material layer 10 of aphase change alloy including tantalum (Ta) and nitrogen (N) toeffectuate a phase change as required by device programming.

Still referring to FIG. 1A, in some embodiments, a metal line includingan electrically conductive material 20 (also referred to as secondelectrically conductive material 20) is present atop the opening 15including the antifuse material layer 10. The second electricallyconductive material 20 is similar to the first electrically conductivematerial 6. Therefore, the above description of the composition of thefirst electrically conductive material 6 is suitable for describing thecomposition of the second electrically conductive material 20. In someembodiments, the second electrically conductive material 20 in directcontact with at least the antifuse material layer 10. Similar to thefirst electrically conductive material 6, the second electricallyconductive material 20 may be employed to thermally heat the antifusematerial layer 10 to cause the phase change from the dielectric phase ofthe material to the electrically conductive phase of the material.

The metal line may be present in an trench that is formed in a seconddielectric layer 35. In some embodiments, a diffusion barrier layer 40(also referred as second diffusion barrier layer 40) is present betweenthe second electrically conductive material 20 for the metal line andthe dielectric layer 35 that the trench for the metal line is formed in.The second diffusion barrier 40 is a conformal layer present on thesidewalls and base of the opening in the dielectric layer 35 for themetal line. In some embodiments, the second diffusion barrier 40 has athickness ranging from 2 nm to 10 nm. In some examples, the seconddiffusion barrier layer 40 may be composed of Co, Ir, Rh, Pt, Pd, Ta,TaN, Ti, TiN, Ru, RuN, RuTa, RuTaN, W, WN and combinations thereof.

In some embodiments, the antifuse structure depicted in FIG. 1A includesa first electrically conductive material 6 that extends across anentirety of a width of the opening in the dielectric contacting thefirst diffusion barrier 30 on each of the sidewalls of said opening 15,and wherein the phase change material alloy is present directly atop afirst electrically conductive material 6 and across said entirety ofsaid width of said opening in the dielectric 5 contacting the firstdiffusion barrier 30 on each of the sidewalls of said opening 15. Thefirst electrically conductive material 6 that is contained within theopening 15 containing the antifuse material layer 10 is entirelyseparated from the second electrically conductive material 20 thatprovides the metal by the phase change material alloy that provides theactive element of the antifuse structure.

FIG. 1B depicts another embodiment of the present disclosure. In FIG.1B, the antifuse material layer 10 of a phase change alloy includingtantalum (Ta) and nitrogen (N) fills the entirety of the opening 15through the dielectric layer 5 substantially to the contact surface 25of electrical device that the antifuse structure is in connection with,i.e., to the diffusion barrier layer 30 present on the contact surface25. The antifuse material layer 10 depicted in FIG. 1B has beendescribed above with reference to FIG. 1A. In the embodiment that isdepicted in FIG. 1B, the first electrically conductive material 6 thatis depicted in FIG. 1A is removed.

In one embodiment, the device depicted in FIG. 1B includes a dielectriclayer 5, atop an electrical device (depicted as the contact surface 25for the electrical device), wherein an opening 15 extends through thedielectric layer 5 to a contact surface of the electrical device 25. Afirst diffusion barrier 30 is present on the sidewalls and a base of theopening 15 that contains the antifuse material layer 10. An electricallyconductive material 20 (also referred to as second electricallyconductive material 20) that can provide a metal line is present indirect contact with at least the antifuse material layer 10. Theelectrically conductive material layer 20 extends over the antifusematerial layer 10 and the dielectric layer 5. It is noted that the firstdiffusion barrier layer 30, the contact surface 25, dielectric layer 5and the electrically conductive material 20 (second electricallyconductive material) that are depicted in FIG. 1B have been describedabove in the description of the structures depicted in FIG. 1A havingthe same reference numbers. Still referring to FIG. 1B, the antifusestructure may further include a second dielectric layer 35 and seconddiffusion barrier 40, which have also been describe above in FIG. 1A.

FIG. 2A is a side cross-sectional view depicting another embodiment ofan antifuse structure 100, in which the antifuse material 10 of thephase change alloy including tantalum and nitrogen is present centrallypositioned within the opening 15 extending through the dielectric layer5. In the embodiment depicted in FIG. 2A, the antifuse material 10 issubstantially surrounded by an electrically conductive material 6 (alsoreferred to as first electrically conductive material 6) present betweenthe sidewalls of the opening 15 and the centrally positioned antifusematerial 10, as well as a portion of the first electrically conductivematerial 6 that is present at the base of the opening 15. The antifusematerial 10 of the phase change alloy including tantalum and nitrogen issimilar to the antifuse material layer 10 of the phase change alloyincluding tantalum (Ta) and nitrogen (N) that is described withreference to FIGS. 1A and 1B. Therefore, the above description of theantifuse material layer 10 of the phase change alloy including tantalum(Ta) and nitrogen (N) that is described with reference to FIGS. 1A and1B is suitable for describing the centrally positioned antifuse material10 that is depicted in FIG. 2A. For example, the centrally positionedantifuse material 10 may be in a dielectric phase of Ta₃N₅ when theantifuse structure has not been programmed, wherein programming mayinclude heating the antifuse material 10 to effectuate a phase change toan electrically conductive phase, in which crystal phase of thecentrally positioned antifuse material 10 is cubic, hexagonal, e.g.,TaN.

The electrically conductive material 6 (also referred to as firstelectrically conductive material 6) that is depicted in FIG. 2A issimilar to the electrically conductive material 6 that is describedabove with reference to FIGS. 1A and 1B. For example, the electricallyconductive material 6 may be composed of a metal selected from copper(Cu), tungsten (W), aluminum (Al) cobalt (Co), rhodium (Rh), ruthenium(Ru), iridium (Ir), nickel (Ni) and combinations thereof. Further,similar to the embodiments described above with reference to FIGS. 1 and2, the electrically conductive material 6 may be employed to heat thecentrally positioned antifuse material 10 to program the antifusestructure. As described above, programming the antifuse structure mayinclude heating the centrally positioned antifuse material 10 to cause aphase change from an insulating/dielectric phase, e.g., Ta₃N₅, to anelectrically conductive phase, e.g., TaN, of the centrally positionedantifuse material 10.

In some embodiments of the antifuse structure that is depicted in FIG.2A, the portions of the first electrically conductive material 6 on thesidewalls of the opening are perpendicularly orientated with respect tothe underlying contact surface 25. By “perpendicularly orientated” it ismeant that the inner and outer sidewalls of the first electricallyconductive material that separate the centrally positioned portion ofthe antifuse material 10 from the dielectric 5 are along a plane thatintersects with the upper surface of the underlying contact surface 25at an angle of substantially 90°, e.g., 90°+/−5°. This is differentiatefrom other embodiments of the present disclosure having tapered portionsof the first electrically conductive material 6 on the sidewalls of theopening 15, as later described with reference to FIGS. 3A and 3B. In theembodiment depicted in FIG. 2A, the centrally positioned portion of theantifuse material 10 does not extend through the entire height of theopening 15 through the dielectric layer 5.

In some embodiments, the width of the first electrically conductivematerial on the sidewalls of the opening 15 ranges from 2 nm to 25 nm.In some further embodiments, the width of the first electricallyconductive material on the sidewalls of the opening 15 ranges from 5 nmto 10 nm. The antifuse material 10 that is centrally positioned extendsa partial vertical height of the opening. The portion of the firstelectrically conductive material 6 present at the base of the opening 15separating the centrally positioned antifuse material 10 from thecontact surface 25 of the underlying electrical device may have athickness ranging from 2 nm to 25 nm. In some embodiments, the portionof the first electrically conductive material 6 present at the base ofthe opening 15 may have a thickness ranging from 5 nm to 15 nm.

The antifuse structure depicted in FIG. 2A also includes a metal linecomposed of an electrically conductive material 20 (second electricallyconductive material 20) present within a dielectric layer 35 overlyingthe opening 15 containing the centrally positioned antifuse material 10.Additionally, in some embodiments, the electrically conductive material20 further includes diffusion barrier layers 30, 40. It is noted thatthe diffusion barriers 30, 40, the contact surface 25, interleveldielectric layer 5 and the electrically conductive material 20 (secondelectrically conductive material) that are depicted in FIG. 2A have beendescribed above in the description of the structures depicted in FIG. 1Ahaving the same reference numbers.

FIG. 2B depicts another embodiment of the antifuse structure 100. Theantifuse structure 100 depicted in FIG. 2B is similar to the antifusestructure depicted in FIG. 2A with the exception that the antifusematerial 10 of the phase change alloy including tantalum and nitrogen iscentrally positioned and extends entirely through the vertical height ofthe opening.

FIGS. 3A and 3B depict other embodiments of the present disclosure inwhich the antifuse material 10 of the phase change alloy is centrallypositioned in an opening extending through a dielectric layer 5, and theantifuse material 10 of the phase change alloy has tapered, i.e.,angled, sidewalls. In the embodiments depicted in FIGS. 3A and 3B, theantifuse material 10 has tapered sidewalls so that the uppermost surfaceof the antifuse material 10 that interfaces with the overlying metalline has a width greater than the lowermost surface of the antifusematerial 10 that is proximate to the contact surface 25 of theunderlying electronic device. The antifuse material 10 of the phasechange alloy including tantalum and nitrogen is similar to the antifusematerial layer 10 of the phase change alloy including tantalum (Ta) andnitrogen (N) that is described with reference to FIGS. 1A and 1B.Therefore, the above description of the antifuse material layer 10 ofthe phase change alloy including tantalum (Ta) and nitrogen (N) that isdescribed with reference to FIGS. 1A and 1B is suitable for describingthe centrally positioned antifuse material 10 that is depicted in FIGS.3A and 3B. For example, the centrally positioned antifuse material 10may be in a dielectric phase of Ta₃N₅ when the antifuse structure hasnot been programmed, wherein programming may include heating theantifuse material 10 to effectuate a phase change to an electricallyconductive phase, in which the crystal phase of the centrally positionedantifuse material 10 is cubic, hexagonal, e.g., TaN.

The antifuse structure depicted in FIG. 3A is similar to the antifusestructure depicted in FIG. 2A, in which the antifuse material 10 extendsthrough a partial height of the opening 15, and a portion of a firstelectrically conductive material 6 separates the antifuse material 10from the contact surface 25 of the underlying electrical device. Theantifuse structure depicted in FIG. 3B is similar to the antifusestructure depicted in FIG. 2B, in which the antifuse material 10 extendsthrough an entirety of the height of the opening 15 into direct contactwith the contact surface 25 of the underlying electrical device. Thedielectric layers 5, 35, the first and second electrically conductivematerial 6, 20, and the first and second diffusion barriers 30, 40 thatare depicted in FIGS. 3A and 3B have been described above with referenceto FIGS. 1A-2B. Some methods for forming the structures depicted inFIGS. 1A and 31B are now discussed in greater detail with reference toFIGS. 4-10.

FIG. 4 illustrates one embodiment of a via contact 50 through adielectric layer to an electrical device. The via contact 50 depicted inFIG. 4 can be to any component of an electrical device, such as asemiconductor device, e.g., field effect transistor (FET), fin typefield effect transistor (FinFET), metal oxide semiconductor field effecttransistor (MOSFET), bipolar junction transistor, vertical finFET(V-FinFET); memory device, e.g., dynamic random access memory (DRAM),embedded dynamic random access memory (eDRAM), flash memory; and/orpassive electronic devices, such as resistors and capacitors. The viacontact 50 may provide an initial structure for forming an antifusestructure 100. The via contact 50 typically includes an electricallyconductive material 6 that is present in a via opening 15 through adielectric layer 5 that extends to a contact surface 25 of an underlyingelectronic device. A description for the electrically conductivematerial 6 has been provided above for the description of the firstelectrically conductive material 6 that has been described above withreference to FIGS. 1A-3B. The dielectric layer 5 as depicted in FIG. 4is similar to the dielectric layer 5 that has been described above withreference to FIGS. 1A-3B. In some embodiments, the dielectric layer 5may be an oxide, nitride or oxynitride material. In other embodiments,the dielectric layer 5 may be a organosilicate glass (OSG), fluorinedoped silicon dioxide, carbon doped silicon dioxide, porous silicondioxide, porous carbon doped silicon dioxide, spin-on organic polymericdielectrics (e.g., SILK™), spin-on silicone based polymeric dielectric(e.g., hydrogen silsesquioxane (HSQ) and methylsilsesquioxane (MSQ), orcombinations thereof. The dielectric layer 5 may be formed atop thecontact surface 25 of the electrical device using chemical vapordeposition (CVD). Forming the opening 15 through the dielectric layer 5can include photolithography and etch processes. In some embodiments, adiffusion barrier layer 30 may be formed on the sidewalls and the baseof the opening 15 before filling the opening with the electricallyconductive material 6. The diffusion barrier layer 30 depicted in FIG. 4has been described above with reference to FIGS. 1A-3B. The diffusionbarrier layer 30 may be deposited using chemical vapor deposition, suchas plasma enhanced chemical vapor deposition (PECVD). Followingformation of the diffusion barrier layer 30, the remainder of theopening 15 may be filled with the electrically conductive material 6.The electrically conductive material 6 may be deposited using chemicalvapor deposition (CVD) or physical vapor deposition (PVD). Examples ofCVD suitable for depositing the electrically conductive material 6include plasma enhanced chemical vapor deposition (PECVD) or metalorganic chemical vapor deposition (MOCVD). Examples of PVD suitable fordepositing the electrically conductive material may include plating,electroplating, electroless plating, sputtering and combinationsthereof.

In some embodiments, after filling the opening 15 with the electricallyconductive material 6, the structure may be planarized, e.g., planarizedusing chemical mechanical planarization (CMP). The via contact 50depicted in FIG. 4 may be employed as an initial structure for formingthe antifuse structures 100 depicted in FIGS. 1A-3B. In someembodiments, the antifuse structures may be integrated into aninterlevel dielectric layer 5 that includes also via contacts 50 thatare not processed to provide antifuse structures 100, so an interleveldielectric layer 5 can contain both via contacts 50 and antifusestructures 100 overlying the same substrate, which can include one ormultiple electronic devices. To selectively process some of the viacontacts 50 for forming the antifuse structures block masks may beemployed, such as photoresist masks.

FIG. 5A depicts one embodiment of recessing the electrically conductivematerial 6 of a via contact structure 50 as depicted in FIG. 4 within avia opening 15 through a dielectric layer 5 to an underlying contact 25to an electrical device for forming an antifuse structure 100. In theembodiment depicted in FIG. 5A, a portion of the electrically conductivematerial 6 remains at the base of the via opening 15. The electricallyconductive material 6 may be recessed by an etch process. For example,the electrically conductive material 6 may be recessed by an etchprocess that is selective to the interlevel dielectric 5. As usedherein, the term “selective” in reference to a material removal processdenotes that the rate of material removal for a first material isgreater than the rate of removal for at least another material of thestructure to which the material removal process is being applied. Forexample, in one embodiment, a selective etch may include an etchchemistry that removes a first material selectively to a second materialby a ratio of 100:1 or greater. In some examples, the electricallyconductive material 6 may be recessed by an etch process that is alsoselective to the first diffusion barrier 30. The etch process forrecessing the electrically conductive material 6 may be an anisotropicetch process, such as reactive ion etch (RIE). In other embodiments, theetch process for recessing the electrically conductive material 6 may bean isotropic etch, such as a wet chemical etch. Referring to FIG. 5A, insome embodiments, the etch process for recessing the electricallyconductive material 6 may be timed to reduce the height of theelectrically conductive material 6 by a dimension that provides thethickness of the subsequently deposited antifuse material layer 10 ofthe phase change alloy including tantalum (Ta) and nitrogen (N) forproducing the antifuse structure depicted in FIG. 1A.

FIG. 5B depicts another embodiment of the present disclosure, in whichthe entirety of the first electrically conductive material 6 is removedfrom the via opening 15. In this embodiment, the subsequently depositedantifuse material layer 10 of the phase change alloy including tantalum(Ta) and nitrogen (N) fills the entirety of the via opening 15 toprovide the antifuse structure depicted in FIG. 1B. In the embodimentdepicted in FIG. 5B, the first electrically conductive material layer 6may be removed from the via opening 15 using a selective etch that isselective to at least one of the dielectric layer 5, the first diffusionbarrier 30 and the contact surface 25 of the underlying electricaldevice.

FIGS. 6A and 6B depict one embodiment of forming the antifuse materiallayer 10. FIG. 6A depicts one embodiment of forming the antifusematerial layer 10 of a phase change alloy of tantalum and nitrogen inthe upper portion of the via opening that is depicted in FIG. 5A. FIG.6B depicts forming an antifuse material layer 10 of a phase change alloyof tantalum and nitrogen, in which the antifuse material layer fills anentirety of the via opening 15 that is depicted in FIG. 5B. The antifusematerial layer 10 is deposited using a deposition method, such aschemical vapor deposition (CVD) or atomic layer deposition (ALD).Chemical vapor deposition (CVD) is a deposition process in which adeposited species is formed as a result of chemical reaction betweengaseous reactants at greater than room temperature (25° C. to 900° C.);wherein solid product of the reaction is deposited on the surface onwhich a film, coating, or layer of the solid product is to be formed.Variations of CVD processes include, but not limited to, AtmosphericPressure CVD (APCVD), Low Pressure CVD (LPCVD) and Plasma Enhanced CVD(PECVD), Metal-Organic CVD (MOCVD) and combinations thereof may. “Atomiclayer deposition” (ALD) as used herein refers to a vapor depositionprocess in which numerous consecutive deposition cycles are conducted ina deposition chamber. Typically, during each cycle a metal precursor ischemisorbed to the deposition surface; excess precursor is purged out; asubsequent precursor and/or reaction gas is introduced to react with thechemisorbed layer; and excess reaction gas (if used) and by-products areremoved. “Chemisorption” and “chemisorbed” as used herein refer to thechemical adsorption of vaporized reactive precursor compounds on thedeposition surface. In some examples, the adsorbed species are bound tothe deposition surface as a result of relatively strong binding forcescharacterized by high adsorption energies (>30 kcal/mol), comparable instrength to ordinary chemical bonds. The chemisorbed species can limitedto the formation of a monolayer on the deposition surface. In atomiclayer deposition, one or more appropriate reactive precursor compoundsare alternately introduced (e.g., pulsed) into a deposition chamber andchemisorbed onto the deposition surface. Each sequential introduction ofa reactive precursor compound is typically separated by an inert carriergas purge. Each precursor compound co-reaction adds a new atomic layerto previously deposited layers to form a cumulative solid layer. Itshould be understood, however, that atomic layer deposition can use oneprecursor compound and one reaction gas. As compared to the one cyclechemical vapor deposition process, the longer duration multi-cycleatomic layer deposition process allows for improved control of layerthickness by self-limiting layer growth and minimizing detrimental gasphase reactions by separation of the reaction components. Atomic layerdeposition is similar in chemistry to chemical vapor deposition, exceptthat the atomic layer deposition reaction breaks the chemical vapordeposition reaction into two half-reactions, keeping the precursormaterials separate during the reaction.

In some embodiments, the antifuse material layer 10 of the phase changealloy including tantalum (Ta) and nitrogen (N) is deposited from attemperatures ranging from 200 to 375° C. using atomic layer deposition(ALD) or chemical vapor deposition (CVD). In some embodiments,pentakis(dimethylamino)tantalum (PDMAT) can be used as a tantalum sourcewith either ammonia or monomethylhydrazine (MMH) as a nitrogenco-reactant. In some other embodiments, the tantalum source may be aprecursor composed of TBTDMT (Ta(=NtBu)(NMe₂)₃) in combination with anitrogen source provided by N₂/H₂ (or NH₃) plasma or a H₂ plasma. Inthis example the N₂/H₂ (or NH₃) plasma produces an insulating phase, andthe H₂ plasma produces an electrically conductive phase.

In other embodiments, the tantalum (Ta) source may be composed ofTris(diethylamido)(tert-butylimido) tantalum and hydrazine. The tantalum(Ta) source may also TaCl₅ that is employed with a nitrogen source ofNH₃. In some embodiments employing TaCl₅, the precursor gas may beaccompanied with a zinc source, trimethylaluminum (TMA) or hydrogenradials to reduce tantalum V to tantalum III. Nitrogen sources may alsoinclude tert-butylamine, alylamine, 1,1-dimethylhydrazine andcombinations thereof.

In some embodiments, the tantalum (Ta) source may also be provided bypentakis(dimethylamino)tantalum (PDMAT), pentakis(ethylmethylamino)tantalum (PEDMAT), (tert-butylimido)tris(ethylmethylamino)tantalum (TBTMET), (tert-butylimido)tris(diethylamido)tantalum (TBTDET) andcombinations thereof.

The antifuse material layer 10 of the phase change alloy includingtantalum (Ta) and nitrogen (N) is typically deposited in aninsulating/dielectric phase. For example, the antifuse material layer 10of the phase change alloy including tantalum (Ta) and nitrogen (N) maybe deposited having a Ta₃N₅ composition, which may have an orthorhombiccrystalline structure. In other embodiments, the antifuse material layer10 of the phase change alloy including tantalum (Ta) and nitrogen (N)may be deposited having a Ta₄N₅ composition, which may have antetragonal crystalline structure. In some embodiments, the controllingthe gas flow of the nitrogen source can provide the preferredstoichiometry. For example, in some embodiments, an antifuse materiallayer 10 of phase change alloy including tantalum (Ta) and nitrogen (N)may be deposited having a Ta₃N₅ composition and an orthorhombiccrystalline structure, in which the N₂ gas flow may range from 500 sccmto 5000 sccm. In some embodiments, the antifuse material layer 10 ofphase change alloy including tantalum (Ta) and nitrogen (N) may bedeposited having a Ta₃N₅ composition and an orthorhombic crystallinestructure, when the N₂ gas flow ranges from 1500 sccm to 3000 sccm.Following deposition of the antifuse material layer 10 of phase changealloy including tantalum (Ta) and nitrogen (N), the structure may beplanarized so that the upper surface of the antifuse material 10 issubstantially coplanar with the upper surface of the dielectric layer 5.

FIGS. 7A-7C depict one embodiment of forming a metal line including anelectrically conductive material 20 and a diffusion barrier layer 40 ina dielectric layer 35. FIG. 7A depicts forming a metal line, i.e., alayer of an electrically conductive material 20, atop the via contactdepicted in FIG. 4. As noted above, the antifuse structures disclosedherein may be integrated with via contacts that share the samedielectric layer 5. FIG. 7B depicts forming a metal line atop anantifuse material layer 10 of a phase change material including tantalumand nitrogen that is present in a via opening through a interleveldielectric layer 5, as depicted in FIG. 6A. FIG. 7C depicts forming ametal line atop an antifuse material layer 10 of a phase change materialincluding tantalum and nitrogen that is present in a via opening througha dielectric layer, as depicted in FIG. 6B. The metal line may be formedby forming the dielectric layer 35 atop the contact via 50, as depictedin FIG. 4, or antifuse structure, as depicted in FIGS. 6A and 6B. Insome embodiments, the dielectric layer 35 may be an oxide, nitride oroxynitride material. In other embodiments, the dielectric layer 35 maybe a organosilicate glass (OSG), fluorine doped silicon dioxide, carbondoped silicon dioxide, porous silicon dioxide, porous carbon dopedsilicon dioxide, spin-on organic polymeric dielectrics (e.g., SILK™),spin-on silicone based polymeric dielectric (e.g., hydrogensilsesquioxane (HSQ) and methylsilsesquioxane (MSQ), or combinationsthereof. The dielectric layer 35 may be deposited using chemical vapordeposition (CVD). Following forming the dielectric layer 35, trenchopening for the metal lines may be patterned and etched in thedielectric layer 35. For example, the trench openings may be formedusing photolithography and etch processes. In some embodiments, adiffusion barrier layer 40 may be formed on the sidewalls and the baseof the trench openings for the metal lines before filling the openingwith the electrically conductive material 20. The diffusion barrierlayer 40 depicted in FIG. 4 has been described above with reference toFIGS. 1A-3B. The diffusion barrier layer 40 may be deposited usingchemical vapor deposition, such as plasma enhanced chemical vapordeposition (PECVD). Following formation of the diffusion barrier layer40, the remainder of the trench may be filled with the electricallyconductive material 20. The electrically conductive material 20 may bedeposited using chemical vapor deposition (CVD) or physical vapordeposition (PVD). Examples of CVD suitable for depositing theelectrically conductive material 6 include plasma enhanced chemicalvapor deposition (PECVD) or metal organic chemical vapor deposition(MOCVD). Examples of PVD suitable for depositing the electricallyconductive material may include plating, electroplating, electrolessplating, sputtering and combinations thereof. In some embodiments, afterfilling the opening 15 with the electrically conductive material 20, thestructure may be planarized, e.g., planarized using chemical mechanicalplanarization (CMP).

FIGS. 8A-10 depict some other embodiments of method for forming antifusestructures 100. The methods described with reference to FIGS. 8A-10 canprovide some examples of the antifuse structures depicted in FIGS.2A-3B. FIG. 8A depicts one embodiment of forming an etch mask 45 atop acontact via, as depicted in FIG. 4 for forming one of the structuresdepicted in FIGS. 2A-3B. The etch mask 45 may be formed usingphotolithography. The lithographic process can include forming aphotoresist layer atop the electrically conductive material 6, exposingthe photoresist to a desired pattern of radiation and developing theexposed photoresist utilizing a conventional resist developer.

The pattern is then transferred into the electrically conductivematerial 6 by etching to form an antifuse material opening, as depictedin FIGS. 8B-8E. The etching can include a dry etching process (such as,for example, reactive ion etching, ion beam etching, plasma etching orlaser ablation), and/or a wet chemical etching process. For example, inone embodiment, an anisotropic etch process, such as reactive ionetching (RIE), can be used to etch the electrically conductive materialwithin the via opening 15 that is depicted in FIGS. 8B and 8C to providea centrally positioned antifuse material opening having verticallyorientated sidewalls. In another embodiment, a combination ofanisotropic and isotropic etch processed may be used to provide acentrally positioned antifuse material opening that is formed in theelectrically conductive material 6 having a tapered or angled sidewall,as depicted in FIGS. 8D and 8E. In some embodiments, the etch processmay continue to recess a centrally positioned portion of theelectrically conductive material 6 that is exposed by the etch mask 45 apartial height of the via opening, as depicted in FIGS. 8B and 8D. Inother embodiments, the etch process may continue until the centrallypositioned openings extends entirety through the height of theelectrically conductive material 6 in the via opening 15, as depicted inFIGS. 8C and 8E. To provide the correct etch depth, the etch process forforming the centrally positioned opening in the electrically conductivematerial 6 may be timed, or the etch process may employ end pointdetection techniques. After patterning the underlying electricallyconductive material 6, the patterned photoresist can be removedutilizing a conventional stripping process such as, for example, oxygenashing.

The centrally positioned opening is subsequently filled with theantifuse material 10. FIG. 9 depicts one embodiment of forming anantifuse material layer 10 of a phase change alloy of tantalum andnitrogen in the antifuse material opening depicted in FIG. 8B. AlthoughFIG. 9 depicts forming the antifuse material 10 in the antifuse materialopening that is depicted in FIG. 8B, the deposition step depicted inFIG. 9 is equally applicable to the other embodiments of the presentdisclosure that are depicted in FIGS. 8C-8E. The antifuse material 10that is depicted in FIG. 9 may be formed using a chemical vapordeposition (CVD) or atomic layer deposition (ALD) process, as describedabove for forming the antifuse material 10 that is depicted in FIGS. 6Aand 6B. For example, the antifuse material layer 10 of the phase changealloy including tantalum (Ta) and nitrogen (N) may be deposited in aninsulating/dielectric phase. In some embodiments, the antifuse materiallayer 10 of the phase change alloy including tantalum (Ta) and nitrogen(N) for the antifuse material 10 may be deposited having a Ta₃N₅composition, which may have an orthorhombic crystalline structure. Inother embodiments, the antifuse material layer 10 of the phase changealloy including tantalum (Ta) and nitrogen (N) may be deposited having aTa₄N₅ composition, which may have an tetragonal crystalline structure.In some embodiments, the controlling the gas flow of the nitrogen sourcecan provide the preferred stoichiometry. For example, in someembodiments, an antifuse material layer 10 of phase change alloyincluding tantalum (Ta) and nitrogen (N) may be deposited having a Ta₃N₅composition and an orthorhombic crystalline structure, in which the N₂gas flow may range from 500 sccm to 5000 sccm. In some embodiments, theantifuse material layer 10 of phase change alloy including tantalum (Ta)and nitrogen (N) may be deposited having a Ta₃N₅ composition and anorthorhombic crystalline structure, when the N₂ gas flow ranges from1500 sccm to 3000 sccm.

Referring to FIG. 9, in some embodiments, the antifuse material layer 10may be deposited to fully fill the centrally positioned antifusematerial opening that has been formed in the electrically conductivematerial 6. Typically, the antifuse material layer 10 is deposited tofully fill the centrally positioned antifuse material opening that hasbeen formed in the electrically conductive material 6, in which theantifuse material layer 10 extends onto the upper surface of thedielectric layer 5 on opposing sides of the via opening.

Following deposition of the antifuse material layer 10 of phase changealloy including tantalum (Ta) and nitrogen (N), the structure may beplanarized so that the upper surface of the antifuse material 10 issubstantially coplanar with the upper surface of the dielectric layer 5,as depicted in FIG. 10. The planarization process typically removes theportion of the antifuse material layer 10 that extends over thedielectric layer 5. The planarization process may include chemicalmechanical planarization (CMP). Although FIG. 10 depicts planarizing theantifuse material 10 in the antifuse material opening that are formed inaccordance with the embodiments consistent with those depicted in FIG.8B, the planarization step depicted in FIG. 10 is equally applicable tothe other embodiments of the present disclosure that are depicted inFIGS. 8C-8E.

Following forming the centrally positioned antifuse material 10, themethod may continue with forming a metal line thereon. For example,forming a metal line on the structure depicted in FIG. 10 may providethe antifuse structures that have been described above with reference toFIG. 2A. Forming a metal line on the centrally positioned antifusematerial in the antifuse material openings described with reference toFIG. 8C can provide one example of the structure depicted in FIG. 2B.Forming a metal line on the centrally positioned antifuse material inthe antifuse material openings described with reference to FIG. 8D canprovide one example of the structure depicted in FIG. 3A. Forming ametal line on the centrally positioned antifuse material in the antifusematerial openings described with reference to FIG. 8E can provide oneexample of the structure depicted in FIG. 3B. Forming the metal line mayinclude depositing a dielectric layer 35; patterning the dielectriclayer 35 to provide a line trench overlying the via opening 15; forminga diffusing barrier layer 40 on the sidewalls and base of the linetrench; and filling the remainder of the line trench with anelectrically conductive material 20. Further details for forming themetal line can be found in the above description of the metal line thatis described with reference to FIGS. 7A-7C.

In some embodiments, the present disclosure provides a method ofprogramming an antifuse structure 100. The method of programming theantifuse may include providing an antifuse structure 100 as describedabove with reference to FIGS. 1-10, which includes an antifuse materiallayer 10 including a phase change material alloy of tantalum andnitrogen in an opening through a dielectric layer to an electricaldevice. In some embodiments, the phase change material alloy of theantifuse material layer 10 is first formed having an insulating phase.The antifuse material layer 10 is typically contacted with at least oneelectrically conductive metal 20 at a surface of the antifuse materiallayer 10 that is opposite a surface of the antifuse material layer thatis contacting the electrical device. In some embodiments, a secondelectrically conductive metal 6 is present between the antifuse materiallayer 10 and the electrically conductive device. In some embodiments,programming the antifuse material layer 10 may include thermally heatingthe antifuse material 10 through at least one of the electricallyconductive metals 6, 20. Thermally heating the antifuse material layer10 can change crystal structure (and accordingly change a nitrogen (N)to tantalum (Ta) ratio) in the antifuse material layer 10 to convert theantifuse material layer from its insulating phase to an electricallyconductive phase. For example, programming the antifuse structure mayinclude thermally heating the antifuse material layer 10 to cause aphase change from an insulating orthorhombic crystal structure, e.g.,Ta₃N₅ composition to an electrically conductive cubic or hexagonalcrystal structure, e.g., TaN composition. In some embodiments, thermalheating to program the antifuse structure may induce a phase change froman insulating phase to an electrically conductive phase at a temperatureranging from 500° C. to 900° C. In another embodiment, thermal heatingto program the antifuse structure may induce a phase change from aninsulating phase to an electrically conductive phase at a temperatureranging from 550° C. to 650° C. In one example, thermal heating toprogram the antifuse structure may induce a phase change from aninsulating phase to an electrically conductive phase at a temperature of600° C.

Having described preferred embodiments of antifuse structures andmethods of forming antifuse structures (which are intended to beillustrative and not limiting), it is noted that modifications andvariations can be made by persons skilled in the art in light of theabove teachings. It is therefore to be understood that changes may bemade in the particular embodiments disclosed which are within the scopeof the invention as outlined by the appended claims. Having thusdescribed aspects of the invention, with the details and particularityrequired by the patent laws, what is claimed and desired protected byLetters Patent is set forth in the appended claims.

What is claimed is:
 1. An antifuse structure comprising: a firstelectrically conductive material that is present within an opening in adielectric material; an antifuse material layer present within theopening in the dielectric, the antifuse material layer comprising aphase change material alloy of tantalum and nitrogen, wherein at leastone surface of the antifuse material layer is present in direct contactwith the first electrically conductive material; and a secondelectrically conductive material in direct contact with at least theantifuse material layer, the second electrically conductive materialover the opening.
 2. The antifuse structure of claim 1, wherein thephase change material alloy has dielectric properties and anorthorhombic phase prior to said antifuse structure being programmed. 3.The antifuse structure of claim 2, wherein the phase change materialhaving said dielectric properties is Ta₃N₅.
 4. The antifuse structure ofclaim 1, wherein the phase change material alloy has electricallyconductive properties and a cubic or hexagonal phase following saidantifuse structure being programmed.
 5. The antifuse structure of claim4, wherein the phase change material alloy is TaN.
 6. The antifusestructure of claim 1, wherein the phase change material alloy haselectrically conductive properties and a cubic phase following saidantifuse structure being programmed.
 7. The antifuse structure of claim1, wherein at least one of the first electrically conductive materialand the second electrically conductive material comprises a metalselected from the group consisting of Cu, W, Al, Co, Rh, Ru, Ir, Ni andcombinations thereof.
 8. The antifuse structure of claim 1 furthercomprising a diffusion barrier present between sidewalls of said openingin said dielectric material, and sidewalls of at least one of saidantifuse material layer and said first electrically conductive material.9. The antifuse structure of claim 8, wherein the diffusion barriercomprises a diffusion barrier metal containing material selected fromthe group consisting of tantalum nitride (TaN), titanium nitride (TiN),ruthenium (Ru), tungsten nitride (W(N)), RuTa(N), Co, Ru andcombinations thereof.
 10. The antifuse structure of claim 9, wherein thefirst electrically conductive material extends across an entirety of awidth of the opening in the dielectric contacting said diffusion barrieron each of said sidewalls of said opening, and said phase changematerial alloy is present directly atop said first electricallyconductive material and across said entirety of said width of saidopening in the dielectric contacting said diffusion barrier on each ofsaid sidewalls of said opening, wherein the first electricallyconductive material is entirely separated from the second electricallyconductive material by the phase change material alloy.
 11. The antifusestructure of claim 10, wherein said antifuse material layer is centrallypositioned in said opening, and said first electrically conductivematerial includes vertical portions separating said antifuse materiallayer from said diffusion barrier on said sidewalls of said opening. 12.The antifuse structure of claim 11, wherein the antifuse material layerthat is centrally positioned extends an entire vertical height of theopening.
 13. The antifuse structure of claim 11, wherein the antifusematerial layer that is centrally positioned extends a partial verticalheight of the opening.
 14. The antifuse structure of claim 11, whereinthe antifuse material layer have vertically orientated or taperedsidewalls.
 15. A device comprising: an interlevel dielectric layer atopan electrical device, wherein an opening extends through interleveldielectric layer to a contact surface of the electrical device; adiffusion barrier present on sidewalls and a base of the opening; anantifuse material layer present within the opening in the interleveldielectric, the antifuse material layer comprising a phase changematerial alloy of tantalum and nitrogen, wherein the antifuse materiallayer fills an entirety of the opening on the diffusion barrier; and anelectrically conductive material in direct contact with at least theantifuse material layer, the electrically conductive material layerextending over the antifuse material layer and the interlevel dielectriclayer.